Opster Team
Before you begin reading this guide, we recommend you run Elasticsearch Error Check-Up which analyzes 2 JSON files to detect many errors.
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This guide will help you check for common problems that cause the log ” Dangling index exists on local file system; but not in cluster metadata; ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: cluster, dangling, discovery-file, index and indices.

Log Context
Log “[{}] dangling index exists on local file system; but not in cluster metadata;” classname is DanglingIndicesState.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
} else if (graveyard.containsIndex(indexMetaData.getIndex())) { logger.warn("[{}] can not be imported as a dangling index; as an index with the same name and UUID exist in the " + "index tombstones. This situation is likely caused by copying over the data directory for an index " + "that was previously deleted."; indexMetaData.getIndex()); } else { logger.info("[{}] dangling index exists on local file system; but not in cluster metadata; " + "auto import to cluster state"; indexMetaData.getIndex()); newIndices.put(indexMetaData.getIndex(); indexMetaData); } } return newIndices;
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